Hi folks.
Sorry have not been on the forum but I believe there was a problem anyway.
Firstly the good news. We solved the speedo problem and it now works. Thanks for the advice.
Bad news is that the engine is still overheating with “mud” ending up in the radiator. So I am going to put radiator flush in to see if that solves the problem. I am also going to pressure test the head just in case it has a crack only manifesting itself under heat.
Otherwise we are getting close to dismantling the engine and of course removing the liners. A big job that I am trying to avoid.
Watch this space!